1. The Technical Field
The present invention relates to tissue sampling devices associated with biopsy needles, and in particular, to an automatic tissue sampling apparatus for utilizing two-piece biopsy needle systems for facilitating the retrieval of a tissue sample for testing.
2. The Prior Art
A typical biopsy needle system utilized in obtaining tissue samples is composed of two parts, a first needle and a second needle. The first needle consists of a substantially solid shaft, having a first handle disposed at one end. A cutting point, to facilitate insertion of the needle into the tissue to be sampled, is located at the other end of the shaft, opposite to the position of the handle. Positioned proximate to the cutting point is a tissue holding region, which is in the form of a cut-out region or flat in the otherwise substantially cylindrical shaft.
The second needle is typically hollow, and has a cutting point disposed at one end. At the other end, a second handle is disposed. The hollow passageway extends through the second handle, to enable the solid shaft of the first needle to be inserted into the passageway and into and through the entire hollow shaft of the second needle.
The shaft of the first, inner, solid needle is typically greater in length than the entire second, outer, hollow needle structure. When the first and second handles are placed in a particularly spaced co-axial configuration, the hollow shaft of the second needle covers the tissue holding region of the first needle. The tissue holding region may be exposed by projecting the first needle further into the second needle, bringing the first and second handles closer together.
To obtain a tissue sample, the biopsy needle system is typically inserted into a patient, into the specific tissue to be sampled, at the desired cell mass to be investigated, with the first and second needles relatively positioned in the first described configuration, so that the tissue holding region is covered. The tissue holding region is then exposed, by the operator holding the second handle of the second needle stable while projecting the first needle forward a short distance along its sharp pointed region-until a portion of the tissue being tested surrounds the flat cut-out of the tissue holding region.
The second needle, which also has a sharp, though hollow, point disposed at the end of the hollow shaft opposite the second handle, is then moved forward, relative to the now-stabilized first needle—to cut off the tissue sample from the rest of the tissue, and cover the tissue sample about the flat cut-out of the tissue holding region. The angled cutting point of the second needle serves to sever the tissue sample. The first and second needles are typically maintained in a particular angular concentric orientation with respect to one another, prior to insertion, so as to maintain the forwardmost portion of the second needle point centered when positioned over the flat, cut-out region of the first needle.
After the tissue is severed and confined between the first and second needles, the first and second needles will be brought back to the same relative positions they occupied immediately prior to initial insertion of the biopsy needle system into the patient. To prevent loss or contamination of the tissue sample, the first and second needles are typically removed from the patient in this tissue-isolating configuration.
As the configuration of the first and second needles, utilized for initial insertion, and final removal from the patient, requires that the first and second handles be spaced apart in a particular configuration, the manual manipulation of such a biopsy needle system requires considerable dexterity, concentration and skill on the part of the operator. The concentration necessary to maintain the proper spacing may detract from the concentration necessary to make insertion and removal of the biopsy needle as painless as possible for the patient. Accordingly, it is desirable to provide a form of automatic tissue sampling apparatus, which accomplishes some, if not all of the handling steps just described—so that the operator may be concerned with the crucial initial step of insertion and final step of removal, of the biopsy needle system; to reduce the amount of discomfort to the patient, to improve the quality of the results of the tissue sampling procedure, and to enhance the successful repeatability of the procedure, from one patient to the next.
Examples of prior art automatic tissue sampling apparatus include those disclosed in PCT application No. PCT/SE83/00112, Swedish Patent No. 8600755, U.S. Pat. No. 4,699,154, issued to Lindgren, U.S. Pat. Nos. 4,944,308, and 4,953,558, issued to Akerfeldt, EPO Application No. 0 318 447 and Swiss Patent No. 483 829.
In the PCT '00112 application, an automatic tissue sampling apparatus is disclosed, in which the first needle of the biopsy needle system is propelled forward by a pressure plate which is driven by a compressed spring, and the second needle is propelled by a movable slide which receives the second handle of the second needle. The movable slide for holding the second needle is also propelled by a compressed spring. In order to prepare the apparatus for use, each of the springs and respective slides must be cocked separately, either manually or through the use of a specially shaped tool. The slide for the second handle is held in place by a catch which is configured to be released upon contact with a projection arranged upon the slide for the first handle of the first needle. The pressure plate for the first handle of the first needle is, in turn, retained in its cocked position by a trigger which is actuatable by the operator. While it is possible to cock each of the spring with the biopsy needle already in place, it is contemplated that such cocking could take place well prior to loading of the needle.
In the operation of the PCT '00112 device, once the springs have been cocked and the biopsy needle system has been loaded (either before or after cocking), the operator inserts the biopsy needle system into the tissue to be sampled, as previously described. He or she may then depress the trigger which releases the spring for propelling the first needle. As the first needle is moved forward, the pressure plate releases the retaining mechanism which has been previously holding the movable slide for the second handle of the second needle. The second needle is thus moved forward shortly after the first needle, completing the sampling movement. The trigger in the apparatus is biased by a spring into position to retain the compressed spring for the first needle slide, and is configured to provide increasing resistance to depression, up until a predetermined position, at which point, the resistance is sharply increased and further depression results in the immediate release of the compressed spring. No means are provided for preventing inadvertent actuation of the automatic tissue sampling apparatus.
Due to the inherently hazardous nature of the extremely sharp points of the biopsy needle and the power of the spring-loaded mechanism, it is desirable, therefore, to provide a tissue sampling apparatus which has an automatically engaging safety mechanism, which must be consciously overcome before the tissue sampling apparatus may be actuated. In addition, it may be often awkward and/or difficult to manually overcome the force of the uncompressed springs which drive the movable slides. Accordingly, it would be desirable to provide an automatic tissue sampling apparatus which may be readily prepared for use, immediately before insertion, without the need for extreme physical exertion or the use of awkward and/or specially configured tools.
The tissue sampling device embodied in U.S. Pat. No. 4,699,154 to Lindgren discloses a housing in which two slides are mounted for longitudinal movement, the slides being configured to receive the first and second handles of the first and second needles, respectively. Each of the slides is propelled by a pair of compressed springs. The rearward slide, for propelling the handle of the first needle, is propelled by springs which bear against a rear wall of the housing. The slide for the handle of the second needle is propelled by compressed springs which bear against a fixed, transversely-extending wall arranged in the housing between the forward and rear slides. Both of the slides are arranged to have a guide member extending through them. A drawbolt is operably associated with each of the slides for limited axial movement relative thereto such that when the drawbolt is pulled backward, both of the slides are simultaneously drawn against the bias of the respective springs, to a cocking position. When the cocking position is reached, retaining members associated with each of the slides engage the respective slides to retain them in their cocked positions.
In a manner similar to that discussed with regard to the PCT '00112 application, an external triggering mechanism is provided, which is actuatable by the operator to release the retaining mechanism for the slide for the first needle. Once the slide for the first needle has been propelled forward a predetermined distance, a projection on the first slide releases the retaining mechanism for the slide for the handle of the second needle, enabling it to be propelled forward by its respective springs.
One possible drawback to the tissue sampling apparatus of the Lindgren '154 patent is that it is configured so that both sets of springs are compressed, and the slides brought into their retained positions by a single pulling motion upon the drawbolt. Accordingly, the combined strengths of all of the springs must be overcome in order to cock the mechanism. Due to the substantial power stored in the springs which is necessary for the rapid operation of the tissue sampling apparatus, it may be difficult for certain operators to rapidly and easily operate the cocking mechanism. Accordingly, the prior art addressed an automatic tissue sampling apparatus with a built-in cocking mechanism which is readily and easily operated, and which does not require substantial strength or effort in order to arm the apparatus. See, e.g., Schramm, U.S. Pat. No. 5,507,298.
The tissue sampling device of the Lindgren '154 patent is also provided with a safety mechanism, for precluding inadvertent actuation. However, the safety mechanism is configured such that it must be positively engaged by the operator, in order to place the tissue sampling apparatus into condition that it cannot be accidentally fired. Accordingly, the effectiveness of the safety device is dependent upon the operator remembering to set the safety. It would be more desirable to provide an automatic tissue sampling apparatus which is configured with a safety device which engages automatically upon the cocking of the apparatus, and is thereby not dependent upon the operator's remembering to engage the safety. Rather, it would be desirable to configure the safety device so the operator must affirmatively disengage the safety before the tissue sampling apparatus can be actuated to fire it.
Swiss Patent No. 483 829 discloses a “gun”-shaped automatic tissue sampling apparatus, in which the springs are cocked by direct pulling force, and so suffers from the same potential drawback of requiring substantial difficulty and effort to arm the device.
U.S. Pat. Nos. 4,944,308 and 4,953,558, issued to Akerfeldt, and EPO Application No. 0 318 447 disclose an automatic tissue sampling apparatus, in which the springs for the slides for the first and second needles are cocked by rotating in a sequential manner. Tabs on the slides ride on cam surfaces to force the slides backward against the springs requiring substantial effort to operate.
In addition to the foregoing, it is well known that often during tissue sampling procedures, the quality and/or quantity of the tissue being sampled may vary from procedure to procedure.
Accordingly, it has been desirable to provide a means for permitting inspection of the tissue sample, without removing the biopsy needle components from the tissue sampling apparatus. In that way, should the size or quality of the sample be inadequate, the biopsy needle may be reinserted into the very same patient for another attempt at obtaining a suitable sample. Such a sample inspection procedure has also permitted access to the sample for subsequent deposit of same onto a microscope slide or other sample holding apparatus for further processing of the tissue sample.
Such prior art tissue sampling apparatus such as those disclosed in the PCT '00112 application and in the Lindgren '154 patent are known to be large, relatively heavy and complicated devices, which are also relatively costly.
The prior art endeavored to provide an improved automatic tissue sampling apparatus which is easy to load and bring into readiness for use, without undue exertion and/or complicated manipulation of its components; while providing a facilitated, positive locking, tissue sample inspection capability.
Thus, the prior art has provided an automatic tissue sampling apparatus which is provided with an automatically engaging safety device, which does not rely upon the operator for its effectiveness and which must be affirmatively disengaged before the tissue sampling apparatus may be actuated.
The prior art also sought, as another goal, the provision of an automatic tissue sampling apparatus which is less complicated and therefore easier and less expensive to construct, and which has a lighter construction for greater ease of operation and manipulation.
Yet another goal of the prior art was to provide an automatic tissue sampling apparatus which is provided with various internal shock and sound absorbing means so as to render the apparatus quieter and less jarring in operation, so as to decrease the actual and/or perceived discomfort of the patient during the tissue sampling procedure, while ensuring better practitioner accuracy during the procedure.
In the prior art apparatus of U.S. patent application Ser. No. 07/753,602, now U.S. Pat. No. 5,284,156, the handles of the first and second needles were borne upon separate yokes which were each configured for longitudinal reciprocating movement within a housing. Both yokes were biased toward the front of the housing and, when the device is cocked, were held in retracted positions by separate retaining mechanism. When the apparatus was “fired”, the yoke bearing the handle of the first needle moved rapidly forward, and as it approached its forwardmost position, it approached a central support. Resilient members on the yoke and on the central support member caused the yoke to decelerate prior to its contact with the central support. Before the resilient members could cause the yoke to “rebound” from the central support, a second “firing” button on the yoke released the retaining mechanism holding the yoke for the second needle. The resilient members by then exerted sufficient force to slightly force the first yoke backward a short distance from the central support. This rebound was necessary to permit the retaining mechanism for the second yoke to engage during subsequent cocking of the apparatus.
While the structure and mode of operation of the prior art automatic tissue sampling apparatus of application Ser. No. 07/753,602, U.S. Pat. No. 5,284,156, represented a substantial improvement over the prior art in terms of shock and noise reduction, as well as with respect to ease and safety of operation, some jarring could still exist during operation and, as a general matter, it is always desirable to seek to improve on the performance of such a device, to reduce such jarring to both improve a patient's physical and psychological well-being, and as well to further improve upon the effectiveness of the device in retrieving tissue samples.
Tissue sampling apparatus which have rearwardly positioned actuation buttons may require that the operator reposition his/her grip, since it is often the situation that the apparatus is grasped at a forward end during placement of the needle in the patient. To address this, the prior art sought to provide an automatic tissue sampling apparatus which has a firing member which is accessible without requiring repositioning of the operator's grip prior to actuation of the apparatus.
An automatic tissue sampling apparatus having a forward located actuating button is disclosed in prior art reference Schramm et al., U.S. Pat. No. 5,507,298. While the apparatus disclosed in that reference likewise represented a significant advance in the art of automatic tissue sampling apparatuses, that device is not without certain functional features which may be of concern. Specifically, the safety mechanism provided in that apparatus, for preventing undesired actuation of the apparatus, comprises, in part, a laterally slidable (depending upon the “cocked” status of the device) shaft. As the device is cocked, the shaft is moved laterally, by following a cam surface on the cocking shaft, to a position which prevents the front and rear firing buttons (which are mechanically interlocked) from being actuated, until such time as the shaft is moved back to its original position. However, it has been found that in the process of exerting pressure on the rear firing button to actuate the automatic tissue sampling apparatus, in this type of device, a user can sometimes inadvertently exert upward force on the cocking lever, causing it to be moved away from its “at rest” position, while the firing action is taking place. When the cocking shaft is away from its “at rest” positions, during the firing action, it is possible for some of the internal components to clash, resulting in component stresses, including possible damage to the structure.
Therefore, it is an additional object of the invention to provide an improved automatic tissue sampling apparatus which is provided with an improved safety lock structure, which is configured to prevent inadvertent cocking movements of the cocking mechanism, so as to preclude disruption of the firing action as well as to reduce the undesired stresses and interferences amongst the structural components, toward improved apparatus operation, including sampling reliability and reduced potential for internal damage to the apparatus, during firing.
These and other objects and goals of the invention will become apparent in light of the present Specification, Drawings and Claims.